The clearest pattern is simply that Trump has regained ground since Clinton’s post-convention peak.

With the odds now favoring a narrow Clinton victory, what would the ramifications be after Nov. 8 if she beats Trump by three or fewer percentage points?

First and foremost, the anticipation of such a defeat has released in the Trump camp what the historian Richard Hofstadter famously described in 1964 as “The Paranoid Style in American Politics”:

In fact, the idea of the paranoid style as a force in politics would have little contemporary relevance or historical value if it were applied only to men with profoundly disturbed minds. It is the use of paranoid modes of expression by more or less normal people that makes the phenomenon significant.

The paranoia of the Trump campaign has found expression in the accusation that the Republican establishment in the primaries and now Hillary Clinton and her allies in the general election are committed to rigging the vote to prevent Trump’s rightful accession to the White House.

I won South Carolina. I won it by a landslide, like a massive landslide, and now they’re trying to pick off those delegates one by one. That’s not the way democracy is supposed to work. And you know, they offer them trips. They offer them all sorts of things. And you’re allowed to do that. And you’re allowed to offer trips and you can buy all these votes. What kind of a system is this? Now, I’m an outsider and I came into the system. And I’m winning the votes by millions of votes. But the system is rigged. It’s crooked.

Big business, elite media and major donors are lining up behind the campaign of my opponent because they know she will keep our rigged system in place. They are throwing money at her because they have total control over everything she does. She is their puppet, and they pull the strings.

I am hardly alone in recognizing Hofstadter’s relevance today. Conor Lynch returned to Hofstadter this summer in Salon, for example.

It’s easy to see why. Hofstadter describes the paranoid style as

made up of certain preoccupations and fantasies: the megalomaniac view of oneself as the Elect, wholly good, abominably persecuted, yet assured of ultimate triumph; the attribution of gigantic and demonic powers to the adversary.

Trump’s strongest supporters do in fact feel abominably persecuted. They are unlikely to fade away gracefully.

Norman Ornstein of the American Enterprise Institute warned that if the outcome is a close win for Hillary Clinton:

It will reinforce the view among Trump populists that the election was stolen and he was stabbed in the back, which will make the task of party leaders that much harder, while creating further delegitimization of the process.

I think we have widespread voter fraud, but the first thing that Trump needs to do is begin talking about it constantly.

Stone’s advice was that Trump should say,

I am leading in Florida. The polls all show it. If I lose Florida, we will know that there’s voter fraud. If there’s voter fraud, this election will be illegitimate, the election of the winner will be illegitimate, we will have a constitutional crisis, widespread civil disobedience, and the government will no longer be the government.

The Trump-Stone message is resonating.

In early August, a Bloomberg poll asked voters, “When it comes to the presidential election, is it your sense the election will or will not be rigged?” The poll found that 56 percent of Trump supporters believed the election would be rigged. Among all voters, 34 percent predicted a rigged election; 60 percent rejected the notion.

U.S. intelligence and law enforcement agencies are probing what they see as a broad covert Russian operation in the United States to sow public distrust in the upcoming presidential election and in U.S. political institutions.

Masket believes that a spreading suspicion among Trump supporters that the election outcome was fixed could have severe repercussions after Nov. 8:

Part of the reason that our nation has been relatively free of political violence is that losers of contests have nearly always accepted their loss and opposed the victor through legitimate means, such as challenging them in future elections or working against their agenda in Congress. The 2000 election was very close and obviously very controversial, but Al Gore nonetheless conceded after the Supreme Court’s ruling. Were Trump and his supporters to continue to argue that the election had been stolen from them, it would mean that they reject nonviolent solutions to political differences. It could jeopardize future elections, undermine the legitimacy of the federal government, and create an environment in which political violence becomes more likely.

While clearly on the fringes of politics, the so called alt-right — white nationalists and hard-line opponents of immigration who oppose multiculturalism and defend a particular vision of Western values — has become an influential force in politics.

Since the start of the Trump campaign, alt-right groups have been attracting members and they have strengthened their ties to the Republican Party.

If Trump continues to be a focal point for alt-right ideas, those voters will demand a voice, either in the Republican Party or outside it. Can the conservative and mainstream Republicans unite effectively and keep the alt-right from steering the party?

The conviction that Democrats and the Washington establishment will rig the election in Clinton’s favor is by no means limited to the alt-right. Newt Gingrich, the former House speaker, and Rudy Giuliani, the former mayor of New York, have both promoted the idea.

“There’s a long tradition on the part of Democratic machines of trying to steal elections,” Gingrich told Sean Hannity on “Fox News” on Aug. 2:

I mean, if you assume that she is a crook, as he says, if you assume that she lies, as he says, why would you expect her to have an honest election?

“This is a rigged system,” Giuliani declared on July 24 on the Fox show “Sunday Morning Futures With Maria Bartiromo,” “and Hillary and Kaine are right in the middle of the Washington insider rigged system.”

On Aug. 26, Ann Coulter, the conservative firebrand, told Politico “Any close election will be stolen by the Democrats.”

Before he was fired, Trump’s campaign manager, Paul Manafort, warned that federal officials could not be trusted to prevent voter fraud:

Frankly, we think that the situation in the country — just like with the Democratic National Committee’s primaries — is a situation where if you’re relying on the Justice Department to ensure the security of the elections, we have to be worried.

In an exhaustive 2007 study of voter fraud, the Brennan Center at N.Y.U. Law School concluded that individual attempts to cast multiple votes, to register using a false name or other methods to vote more than once are so rare as to be inconsequential.

In the New Jersey election in 2004, 3,611,691 votes were cast and there were “eight substantiated cases of individuals knowingly casting invalid votes,” Justin Levitt, the study’s author, who is now deputy assistant attorney general in the Civil Rights Division of the Department of Justice, wrote. He calculated that illegal votes amounted to 0.0004 percent of the total.

As could be expected, the Brennan study has done little or nothing to tamp down accusations of election fraud from the alt-right, and indeed from Trump himself.

Fifty-two years ago, writing in the year of the Johnson-Goldwater election, Hofstadter proved remarkably prescient: The right wing, he argued,

feels dispossessed: America has been largely taken away from them and their kind, though they are determined to try to repossess it and to prevent the final destructive act of subversion.

Should Trump fail to eke out a victory, his already deeply suspicious supporters are likely to double down on allegations that they have been cheated out of what is rightfully theirs. As Hofstadter put it:

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In American experience ethnic and religious conflict have plainly been a major focus for militant and suspicious minds of this sort, but class conflicts also can mobilize such energies. Perhaps the central situation conducive to the diffusion of the paranoid tendency is a confrontation of opposed interests which are (or are felt to be) totally irreconcilable, and thus by nature not susceptible to the normal political processes of bargain and compromise.

Hofstadter wrote that at a time when polarization was a minor factor in politics. The confrontation of irreconcilably opposed interests is far more hostile today, which Hofstadter foresaw with such focused intensity that it is worth quoting him at length:

The situation becomes worse when the representatives of a particular social interest — perhaps because of the very unrealistic and unrealizable nature of its demands — are shut out of the political process. Having no access to political bargaining or the making of decisions, they find their original conception that the world of power is sinister and malicious fully confirmed. They see only the consequences of power — and this through distorting lenses — and have no chance to observe its actual machinery. A distinguished historian has said that one of the most valuable things about history is that it teaches us how things do not happen. It is precisely this kind of awareness that the paranoid fails to develop. He has a special resistance of his own, of course, to developing such awareness, but circumstances often deprive him of exposure to events that might enlighten him — and in any case he resists enlightenment.

The author, most recently, of “The Age Of Austerity: How Scarcity Will Remake American Politics” and a contributing opinion writer.